CIDR Calculator
Calculate IPv4 CIDR ranges, masks, broadcast addresses, and usable host counts.
Enter a dotted-decimal IPv4 address with a CIDR prefix to calculate the containing network, broadcast address, masks, host range, total addresses, and usable host count. IPv6 and reserved-address classification are not calculated.
How it works
CIDR notation combines an IPv4 address and a prefix length from /0 through /32. The prefix length determines the subnet mask, block size, network boundary, broadcast address, and wildcard mask.
If you enter a host address inside a block, the calculator normalizes it to the containing network boundary before reporting the range. For /31 and /32 blocks, both endpoints or the single address are treated as usable for point-to-point and host-route use cases.
